In recent years, gas chromatograph mass spectrometers (hereafter called “GC/MSs”) combining a gas chromatograph part (hereafter called a “GC part”), a mass spectrometry part (hereafter called an “MS” part), and a control part for controlling the GC part and the MS part have been widely used in the qualitative or quantitative analyses of various samples.
FIG. 5 is a schematic block diagram showing an example of a conventional GC/MS. A GC/MS 101 is provided with a GC part 10, an MS part 50, an interface part 70 disposed between the GC part 10 and the MS part 50, and a control part 160.
The control part 160, which is realized by a personal computer, is provided with a CPU 161 and a memory 162, and an input device 63 having a keyboard, a mouse, or the like and a display device 64 for displaying setting content or analysis results are further connected to the control part 160. The operations of the GC part 10, the MS part 50, and the interface part 70 are generally controlled by such a control part 160 based on setting content inputted by the input device 63.
When the CPU 161 is described in terms of blocks of the functions processed by the CPU 161, the CPU 161 has a temperature control part 161a for controlling a first heater 24, a second heater 38 (see FIG. 2), a third heater 72, or the like, a flow rate control part 161b for controlling a flow rate control unit (gas supplying part) 40, and an analysis control part 61c for receiving an ion intensity signal from a detector 55.
The GC part 10 is provided with an oven 20 for gas chromatography, a sample vaporization chamber 30 into which a sample is introduced, and a flow rate control unit (gas supplying part) 40 for supplying a carrier gas.
The oven 20 for gas chromatography is provided with a cubic housing 21 enclosed by four walls on the top, bottom, left, and right, a back wall, and a front door serving as a front wall, and a tubular column 22 through which a sample gas passes, a first heater 24 for heating the housing 21, and a temperature sensor 25 for detecting a temperature T are housed inside the housing 21.
In such an oven 20 for gas chromatography, when an operator inputs a temperature T1′ (for example, 200° C.) at the time of analysis using the input device 63, the temperature control part 161a of the CPU 161 stores the analysis temperature T1′ in the memory 162 and sets the inside of the housing 21 to the analysis temperature T1′ by supplying power to the first heater 24 based on the analysis temperature T1′ stored in the memory 162 and the temperature T detected by the temperature sensor 25.
As a result, with the oven 20 for gas chromatography, if a sample gas is introduced into the inlet end of the gas column 22, the respective components in the sample gas are separated while the gas passes through the inside of the column 22 at the analysis temperature T1′, and the respective separated components sequentially reach the outlet end of the column 22 thereafter.
The interface part 70 is provided with a tubular casing 71 and a third heater 72 for heating the casing 71. The outlet end of the column 22 is inserted into the casing 71 so as to extend to an ionization chamber 52 of the MS part 50.
With such an interface part 70, it is possible to maintain the temperature of the outlet end of the column 22 at approximately the same temperature as the analysis temperature T1′ inside the oven 20 for gas chromatography, and as a result, it is possible to ensure that the flow of the sample gas is not stagnated by the interface part 70.
The MS part 50 is provided with a parallelepiped-shaped vacuum chamber 51, a vacuum pump 56 for creating a vacuum inside the vacuum chamber 51, and a sample source 58 for adjustment in which PFTBA (perfluorotributylamine) or the like for assessing whether oxygen is present inside the column 22 is sealed. An ionization chamber 52, an ion lens 53, a quadrupole mass filter 54 serving as a mass separator, and a detector 55 for obtaining an ion intensity signal are sequentially disposed inside the vacuum chamber 51 along the advancing direction of ions, and an ion gauge (ionization vacuum gauge) 57 for detecting the pressure (degree of vacuum) PMS of the vacuum chamber 51 is also disposed.
With such an MS part 50, sample molecules are ionized by the ionization chamber 52, and the generated ions are drawn to the outside of the ionization chamber 52. The drawn ions are converged by the ion lens 53 and introduced into the quadrupole mass filter 54. A voltage determined by overlaying a direct current voltage and a high-frequency voltage is applied to the quadrupole mass filter 54 by a power supply circuit (not shown), and only ions having a mass (specifically, a mass-charge-ratio) corresponding to the applied voltage pass through the space of the quadrupole mass filter 54 in the major axis direction and reach the detector 55. At this time, if the voltage applied to the quadrupole mass filter 54 is gradually changed, for example, the mass of the ions which may pass through the quadrupole mass filter 54 also changes, so a mass spectrum demonstrating the relationship between mass and ion intensity is obtained by detecting the size of the current corresponding to the number of ions reaching the detector 55 while gradually changing the voltage applied to the quadrupole mass filter 54 with the analysis control part 61c. 
Next, the sample vaporization chamber 30 and the flow rate control unit 40 of the GC part 10 will be described (for example, see Patent Document 1). FIG. 2 is a magnified cross-sectional view of the sample vaporization chamber 30 and the flow rate control unit 40.
The sample vaporization chamber 30 is provided with a tubular metal casing 31 and a second heater 38 for heating the outer peripheral surface of the casing 31.
The casing 31 can be divided into an upper casing 31b and a lower casing 31a, and separating the casing makes it possible to dispose a tubular glass insert 37a made of glass inside.
The upper casing 31b has a sample introduction port 32 which is formed on the top surface and through which a liquid sample S is introduced.
The lower casing 31a has a carrier gas introduction port 33 which is formed on the left side wall and through which a carrier gas is introduced, a purging port 34 which is formed on the right side wall and through which the carrier gas is discharged, a column connection port 35 which is formed on the bottom surface and is connected to the inlet side of the column 22, and a split port 36 which is formed on the right side wall and through which part of the sample gas infused into the casing 31 is discharged together with the carrier gas.
A roughly columnar silicon rubber septum 32a is disposed on the sample introduction port 32, and the septum 32a is fixed to the upper casing 31b as it is pressed downward by a septum nut 32b. With this septum 32a, the operator can drip the liquid sample S into the casing 31 at the time of analysis by thrusting a needle 91 of a micro-syringe 90 containing the liquid sample S into the septum 32a. Since the septum 32a has elasticity, the hole which opens when the needle 91 is inserted into the septum 32a immediately closes when the needle 91 is removed.
The glass insert 37a is supported and disposed by a circular sealing ring 37b inside the lower casing 31a. With such a glass insert 37a, the operator can vaporize the liquid sample S as it passes through the space inside the glass insert 37a from the upper side to the lower side at the time of analysis by disposing the needle 91 of the micro-syringe 90 in the upper part of the internal space formed in the glass insert 37a. 
The upper casing 31b is fixed to the lower casing 31a as it is pressed downward by the sealing nut 37c. 
The column connection port 35 is connected to the inlet end of the column 22 and is fixed by a column nut 35a. 
The carrier gas is sealed in a carrier gas supply source 41. One end of a gas introduction tube 42 is connected to the carrier gas supply source 41, and the other end of the gas introduction tube 42 is connected to the carrier gas introduction port 33 via a gas flow rate adjustment valve 43. The flow rate control unit 40 for supplying the carrier gas is formed by the gas introduction tube 42, the gas flow rate adjustment valve 43, and the carrier gas supply source 41.
One end of a gas discharge tube 46 is connected to the split port 36, and a gas flow rate adjustment valve 47 is further connected to the gas discharge tube 46. As a result, when the gas flow rate adjustment valve 47 is open, a certain proportion of the carrier gas is discharged through the split port 36.
One end of a gas discharge tube 44 is connected to the purging port 34, and a pressure sensor 45 for detecting the pressure P of the inside of the casing 31 is further disposed on the gas discharge tube 44.
In such a sample vaporization chamber 30 and a flow rate control unit 40, the operator inputs a setting so that the flow rate of the carrier gas is a “constant linear velocity” using the input device 63 at the time of analysis. As a result, the flow rate control part 161b of the CPU 161 stores “constant linear velocity” in the memory 162 and controls the gas flow rate adjustment valve 43 so that the flow rate is the “constant linear velocity” stored in the memory 162, which causes the carrier gas to be supplied to the upper part of the casing 31 through the gas introduction tube 42, and further controls the gas flow rate adjustment valve 47 so that a prescribed amount of the carrier gas is fed to the column 22 and a prescribed amount of the carrier gas is fed to the split port 36.
At this time, the casing 31 is heated by the second heater 38 to a temperature equal to or higher than the vaporization temperature of the liquid sample S, and when the liquid sample S is infused into space inside the glass insert 37a, the liquid sample S is immediately vaporized in the space inside the glass insert 37a so that it is sent to the inlet end of the column 22 at a “constant linear velocity” along with the carrier gas flow.
Here, a “constant linear velocity” means that the rate is controlled so that the volume of the carrier gas passing through the cross-sectional area of the column 22 per unit time is constant.
Incidentally, since the glass insert 37a disposed inside the casing 31 of the sample vaporization chamber 30 makes direct contact with the sample S, it is prone to contamination by the adherence of the vaporization residue or the like of the sample S. As a result, when the glass insert 37a becomes contaminated, it is necessary to replace the old glass insert 37a with a new glass insert 37a. 
Here, the replacement operation for replacing the glass insert 37a will be described. FIG. 3 is an exploded view of the sample vaporization chamber 30.
First, when air is immixed inside the column 22 at a temperature equal to or less than the high analysis temperature T1′, the stationary phase film inside the column 22 is oxidized, and as a result, the lifespan of the column 22 is reduced, so the operator inputs a replacement temperature T2′ (for example, 20° C.) with the input device 63 so as to reduce the temperature T of the sample vaporization chamber 30 or the column 22 to a temperature in the vicinity of room temperature.
At this time, if the temperature T of the column 22 becomes a temperature in the vicinity of the replacement temperature T2′ while the flow rate of the carrier gas is set to a “constant linear velocity,” it may not be possible to control the carrier gas with the pressure required to keep the linear velocity constant depending on the length or inside diameter of the column 22, which may cause the flow rate control part 161b of the CPU 161 to generate an error signal. Therefore, before inputting the replacement temperature T2′, the operator uses the input device 63 to input a setting so that the flow rate of the carrier gas has a “constant pressure” or to input a pressure that can be controlled at the replacement temperature T2′.
Here, a “constant pressure” means that the pressure is controlled so that the pressure PGC detected by the pressure sensor 45 is constant.
Next, after the operator confirms that the temperature T of the sample vaporization chamber 30 or the column 22 has become a temperature in the vicinity of the replacement temperature T2′ while viewing the display device 64, the operator loosens and removes the sealing nut 37c from the lower casing 31a and extracts the glass insert 37a from the lower casing 31a. Next, the operator inserts the new glass insert 37a into the lower casing 31a and tightens the sealing nut 37c onto the lower casing 31a. 
Finally, the operator uses the input device 63 to input the analysis temperature T1′ so as to increase the temperature T of the sample vaporization chamber 30 or the column 22 to the analysis temperature T1′ and to further input a setting so that the flow rate of the carrier gas is a “constant linear velocity” or to input the pressure before the change to the replacement temperature T2′.
In addition, if the elasticity of the septum 32a deteriorates due to long-term use or the number of locations with holes increases as the number of uses increases, the holes will not be completely closed, and as a result, the carrier gas will leak to the outside from the inside of the casing 31. When performing analysis under such conditions with a gas leak, there may be a deviation in the retention time, which is the time required for a peak to occur in a chromatogram, or the peak area may be reduced, which may inhibit accurate analysis, so it is necessary to perform a replacement operation for replacing the septum 32a. 
Such an operation for replacing the septum 32a is also executed by the operator with the same procedure as that of the replacement operation for replacing the glass insert 37a. 